The typical amateur golfer, when purchasing golf clubs for the very first time and with little or no golfing experience or equipment knowledge, usually buys clubs as produced to the club manufacturer""s specifications. These standards include different loft and lie angles for each club of a set, according to years of common practice and experience. Even if purchased from a reputable shop which has a golf professional available to assist the purchaser, much is left to guesswork as to the particular player""s loft and lie needs, since his or her capabilities or potential for the sport are unknown. The buyer""s height is often taken into consideration so that the club head sole of a particular club will be placed on the ground the necessary distance forward of the player""s toes when both hands are placed on the club grip and the person is in the proper stance and position to make a swing.
Clubs are typically manufactured so as to fit their lengths to an average-height individual. If the purchasing amateur is shorter than average, the butt ends of the clubs may be shortened and the clubs regripped. Alternatively, the seller may just advise the player to grip the clubs further down on the shafts to effectively shorten the clubs, but without the expense of trimming their lengths. If the player is considerably taller than average so as to make standard clubs insufficient in length, longer clubs may be specially ordered directly from the manufacturer. In either event, the typical club purchase by an amateur or beginner often results in no variation being made to the loft or lie angles of the clubs. They are sold xe2x80x9cas isxe2x80x9d, with the player accepting the standard loft and lie angles designed into the clubs by the original manufacturer, even though manufacturing tolerances and known equipment for setting the angles may provide clubs which are out of tolerance as much as one or two degrees from what they should be for a given individual.
For superior golfers, however, and in particular for playing professionals, it is common to fit each player as precisely as possible for both their preferred lie angle and loft angle of each club. To achieve this, the sole of the club, i.e., its lowermost forward edge at the bottom of the club head face, should be essentially parallel to the turf or a flat surface at ball address. If an imaginary sole line is extended along the sole toward the player, the lie angle of the club can be determined between that imaginary line and the shaft axis of the club. If the sole tends to incline in either direction from essentially parallel with the surface when the player is at proper ball address, the hosel of the head of each club should be bent slightly to accommodate the player. The amount of lie angle for each club will be in accordance with a well-established formula, the angle gradually decreasing from the shortest to the longest club of the set. The club heads are made from a metal which has only nominal ductility but is capable of allowing a few degrees of hosel bending without adversely affecting the integrity of the head. Typically, the allowable bending range for the lie angle is from the manufacturer""s hosel preset angle to within plus or minus two degrees from the hosel axis, or four degrees overall. After the lie angle of all clubs of the set have been adjusted to the player, most club assemblers do nothing more, relying on the manufacturer""s built-in loft-angle design to provide for the standard ball trajectory as a ball is struck by the particular club. Loft angle is determined between the intersection of a first plane coinciding with the club face and a second plane passing through both the imaginary sole line and the axis of the club shaft or hosel. Ordinarily, the loft angles are left intact when clubs are sold to an amateur, and are often left untouched even for better, low handicap players. For professional golfers, the loft angles may be adjusted by hosel bending to provide for higher or lower ball trajectory than standard.
The loft angle of a No. 1 iron, as manufactured, may be between twelve and fourteen degrees, while for a lob wedge, the loft angle may be as great as fifty-eight to sixty-two degrees. Manufacturers normally select a mid-point of the allowable hosel-bending range and provide for varying the loft angle plus or minus one degree from the mid-point. Thus, the loft angle of a No. 1 iron as manufactured may average thirteen degrees and for a lob wedge may average sixty degrees. The loft angles of the No. 2 iron through the sand wedge are progressively increased, as is well understood in this art.
In instances where clubs are xe2x80x9ctailoredxe2x80x9d to fit both the desired loft and lies angles for a particular player, the lie angles are determined by arbitrarily selecting the correct club length for the player""s height via getting the player to take a stance at address of a ball with a mid-iron of a set. If the sole of the club is parallel to the ground, the manufacturer""s standard lie angles are most likely correct for the entire set. If not parallel, the lie angle should be measured and the hosel bent according to the particular individual. All other clubs of the set must then be bent according to the known formulated normal lie angle variation from club to club.
Loft angles may be adjusted differently from one player to another, depending on whether the player prefers to obtain a lower ball trajectory for maximum distance, or a higher trajectory for greater control, but lesser distance.
It has been said that some club manufacturers use lesser loft angles for a given-numbered standard club to cause the unsuspecting amateur to incorrectly think that the manufacturer""s clubs are superior because they allow the player to hit the ball further than the same-numbered club of another manufacturer. For the most part, however, the loft angles are generally within the same range from one manufacturer to the next. If, however, a particular player wants a xe2x80x9cstrongerxe2x80x9d loft angle to obtain greater distance for a given club, the loft angle can be decreased and the ball distance increased accordingly. On the other hand, if a xe2x80x9cweakerxe2x80x9d loft angle is desired to gain higher ball trajectory while sacrificing some distance for a given club, the loft angle can be increased. Typically, most clubs as they arrive at the retail golf shop from the club manufacturer allow for the aforementioned four degree (+ or xe2x88x922 degrees from normal) lie angle adjustment and a two degree (+ or xe2x88x921 degree from normal) loft angle adjustment. Both adjustments are ideally measured from the axis of the hosel or shaft, and bending is done at right angles. But, because angles are most commonly measured with the shaft already in the club head, a side of the shaft becomes the gauging line. Some shafts are tapered along the gauging surface, presenting a further measurement inaccuracy problem. A secondary problem can also result from the way club heads are made. They typically have the shaft-receiving hosel hole cast in them at the time the raw club head is made, and are the holes are then drilled and/or reamed. Obviously, if any one of the casting, drilling or reaming processes causes the hole to be even slightly off line in the hosel; that will affect the shaft angle relative to the club head, in either loft, lie or a composite of those two angles. This has the capability of providing an inaccurate loft and/or lie angle of the finished club, possibly by as much as several degrees between the club head and the grip.
To obtain an adjustment of either the loft or lie of a club, several known tools and some automatic machines are known and in common use in the industry. One such manually-operable tool is known as the Steelclub unit manufactured by Mitchell Golf of Centerville, Ohio. It comprises a clamp having separate loft and lie angle-gauging protractors associated with the clamp. The clubs must be shafted at the time of adjustment and a side of each shaft is utilized for alignment purposes. See, for example, U.S. Pat. No. 4,620,431 issued to Douglas Muldoon on Nov. 4, 1986, which illustrates this general type of clamping and protractor-gauging structure. With meticulous care and with non-tapered shafts at the points of alignment with the protractor markings, such devices can be used effectively for adjustment to an accuracy of about one-fourth of a degree. The problem occurs in that the loft and lie angles are adjusted by bending the hosel separately at right angles for each the loft and lie. Oftentimes an adjustment which has been made for loft will adversely affect the lie angle, and vice versa. Depending on the accuracy desired, each of the two angles may have to be readjusted multiple times, measuring the other angle each time after the hosel has been bent for one angle.
At least one automatic machine for varying loft and lie angles is known in the prior patent art. It is done at the club manufacturing level and is illustrated in U.S. Pat. No. 4,622,836, assigned to McGregor Golf Company of Albany, N.Y. The ""836 patent issued on Nov. 18, 1986 to Dabbs C. Long et al. It shows a rather complex and presumably quite expensive machine in which a shaftless club head is clamped in a position with its hosel bore facing vertically upwardly. A pin is inserted into the machined bore of the hosel and electrical signals determine any angular deviation of the pin from the desired true vertical position. Any measured deviation is then used to activate an appropriate one or two of four hydraulic rams horizontally against the hosel to bend the hosel and thereby restore the bore axis in the desired location for the given club. An objective is to allow scrapping of a club head if it is not manufactured correctly within the specified tolerances. This allows the scrapping to be done before rather than after the head and the shaft have been connected, as a cost-reduction measure. The complexity and cost of the machine would appear to make its usefulness limited only to club manufacturers, and not be practical for the small basement or garage shop that buys club components and builds them for particular golfers or for themselves. Nor would it appear practical for the larger retailer of golf equipment that also repairs clubs.
The invention contemplates using a laser beam projector mounted preferably in a drilled or reamed bore or hole of a golf club head hosel and bending the hosel in a single direction until a projected beam aligns with a target mark placed on a fixed surface which has a predetermined relationship to a clamp for the club head. Each club head is clamped in a predetermined position by means registering the head to at least one surface of a clamp. The clamp itself is mounted in a predetermined relationship relative to the target surface. The target mark is aligned coaxially with the desired end position of the hosel axis while in the clamp. In a preferred form of the invention, the laser beam projector is axially aligned with the hosel bore by means of an expanding collet which is inserted into and then snuggly mounted internally in the hosel opening. Depending on the direction and amount the projected laser beam is misaligned from the target, a hosel bending tool is placed on the hosel and the tool is moved in a single motion and direction until the projected beam and target are brought into alignment.
It is a principal object of the invention to provide a simple, inexpensive, easy-to-perform system and method for adjusting either or both the loft and/or lie angles of a golf club head relative to the hosel axis in the club head in order to achieve harmonization of a full set of golf clubs.
A more specific object is to utilize the bore of a club head to predetermine the axis of the hosel as the preferred means.
Another object is to provide for accomplishing the foregoing objective in a single direction and motion of a hosel-bending tool.
A further object is to enable the foregoing objectives to be accomplished before the shaft has been affixed to the club head during the club manufacturing process.
Yet another object of the invention is to provide an apparatus which is simple and of nominal capital cost so as to be economically available to small golf club shops which assemble shafts to club heads.
A further object is to provide for accomplishment of the foregoing objectives through use of a simple, highly accurate low cost laser beam projector.
Other objects an advantages will become apparent from the following description, in which reference is made to the accompanying drawings.